Geminid meteor shower due to light up Utah sky early Thursday morning

Utahns who missed Sunday's rare planetary grouping — and that's most of the state because of cloud cover — will get another chance at a space spectacular early Thursday morning.

The yearly Geminid meteor shower happens at an especially good time, with a series of "shooting stars" before moonrise, which will be close to 2 a.m. on Thursday. That means moonlight won't be glaring and washing out the view.

Most meteors blast swiftly across the sky, traveling so fast that they burn white-hot, said Patrick Wiggins, NASA solar system ambassador to Utah. But the Geminids "tend to be considerably slower," he added.

The burning grains of dust are not accelerated to white-heat. "Sometimes they're orange hot or red hot," he said. The meteor shower is known for more colorful "falling stars."

Also, he added, Geminid meteors have a "graceful, stately passage across the sky."

Even though the moon won't be a problem much of the night, observers will want to get away from light pollution.

"If you stay in the city, the sky will be brighter than most of the meteors," he added.

Predicting a meteor shower is harder than predicting a rain shower, he said. "It could be that we'll hit a really rich part of the meteorite stream and we'll have a couple of hundred an hour. Or there's always the possibility we'll hit a dead spot."

To watch, stretch out on a lawn chair, snug in a parka or sleeping bag or both, and look up. The meteors seem to originate in the constellation Gemini (the reason for the name), but they streak across much of the sky.

Meteors are almost always the debris trail left when a comet passes through Earth's orbit on its way around the sun. Bits of dust and ice debris fly from the comet's surface as it heats up, forming its tail. The debris remains in space in the orbit, and when Earth returns to that section of the solar neighborhood, grains of material impact the atmosphere and burn up.

In this case, he said, no comet seemed to be prowling about the region of the Geminid debris trail. Then scientists discovered what seemed to be an asteroid in about the right position, leading them to believe it was actually a dead comet, one that had lost all of its volatile surface.

"Now it's just a dead rock," Wiggins said. But material that blew off it, perhaps eons ago, remains suspended in space, awaiting collisions with the atmosphere.

---

E-mail: bau@desnews.com